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Steady-state creep model for UO$sub 2$

Description: From a review of out-of-pile and in-pile experiments, an analytical model was developed for the steady-state creep of UO$sub 2$: epsilon = [(A$sub 1$ - A$sub 2$F)sigma e/sup -Q$sub 1$/RT/]/[A$sub 3$ + D)G$sup 2$] + [A$sub 4$sigma/ sup 4.5/e/sup -Q$sub 2$/RT/]/[(A$sub 5$ + D)] + A$sub 6$sigma Fe/sub-Q$sub 3$/RT/ , where A$sub 1$ = 9.728 x 10$sup 6$, A$sub 2$ = 3.24 x 10$sup -12$, A$sub 3$ = - 87.7, A$sub 4$ = 1.376 x 10$sup -4$, A$sub 5$ = -90.5, A$sub 6$ = 9.24 x 10$sup - 28$, Q$sub 1$ = 90,000, Q$sub 2$ = 132,000, Q$sub 3$ = 5200 (cal/mole), F = fission rate (8.4 x 10$sup 17$ to 1.18 x 10$sup 20$ f/m$sup 3$s), and G = grain size. (DLC)
Date: January 1, 1975
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Temperature estimates from the zircaloy oxidation kinetics in the. cap alpha. plus. beta. phase region. [PWR; BWR]

Description: Oxidation rates of zircaloy in steam were measured at temperatures between 961 and 1264 K and for duration times between 25 and 1900 seconds in order to calculate, in conjunction with measurements from postirradiation metallographic examination, the prior peak temperatures of zircaloy fuel rod cladding. These temperature estimates will be used in light water reactor research programs to assess (a) the accuracy of temperature measurements of fuel rod cladding peak temperatures from thermocouples attached to the surface during loss-of-coolant experiments (LOCEs), (b) the perturbation of the fuel rod cladding LOCE temperature history caused by the presence of thermocouples, and (c) the measurements of cladding azimuthal temperature gradients near thermocouple locations.
Date: January 1, 1981
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

UO/sub 2/ pore migration and grain growth kinetics

Description: A mathematical model for determining the UO/sub 2/ grain growth rate was developed in order to evaluate UO/sub 2/ steady-state creep rates and fracture strengths. This model may also be applied in the postirradiation examination of UO/sub 2/ nuclear fuel rods to estimate fuel temperatures experienced during experiments performed in the Loss-of-Fluid Test (LOFT) facility at the Idaho National Enginering Laboratory. The model was developed from a study of experimental data of UO/sub 2/ grain growth rates and of pore migration rates in UO/sub 2/ and effects of pore size and bubble pressure upon the migration rates. Because pores attached to UO/sub 2/ grain boundaries inhibit the rate of grain growth, a study of grain growth kinetics must consider the UO/sub 2/ pore migration rates.
Date: January 1, 1979
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Temperature estimates from the Zircaloy oxidation kinetics in the. cap alpha. plus. beta. phase region. [PWR; BWR]

Description: Oxidation rates of Zircaloy in steam were measured at temperatures between 961 and 1264 K and for duration times between 25 and 1900 seconds in order to calculate, in conjunction with measurements from postirradiation metallographic examination, the prior peak temperatures of Zircaloy fuel rod cladding. These temperature estimates will be used in light water reactor research programs to assess (a) the accuracy of temperature measurements of fuel rod cladding peak temperatures from thermocouples attached to the surface during loss-of-coolant experiments (LOCEs), (b) the perturbation of the fuel rod cladding LOCE temperature history caused by the presence of thermocouples, and (c) the measurements of cladding azimuthal temperature gradients near the thermocouple locations.
Date: January 1, 1981
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Non-fertile fuels development for plutonium and high-enriched uranium dispositioning in water cooled reactors

Description: As a result of dismantling the bomb, there is about 100 MT of excess weapons grade plutonium in the United States and about 150 MT in the Commonwealth of Independent States. In addition, there is another 1000 MT of plutonium in commercial spent fuel that may be used as degraded weapons material. This report discusses one means to disposition weapons grade plutonium is by irradiating the fuel in light water reactors (LWRs) using a non-fertile fuel based on plutonium dispersed in an oxide mixture of zirconia stabilized with calcia or yttria as a solid solution. Plutonium dispersed in a zirconia matrix offers the potential to achieve very high burnups while maintaining mechanical integrity.
Date: September 1, 1994
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Heat resistant materials and their feasibility issues for a space nuclear transportation system

Description: A number of nuclear propulsion concepts based on solid-core nuclear propulsion are being evaluated for a nuclear propulsion transportation system to support the Space Exploration Initiative (SEI) involving the reestablishment of a manned lunar base and the subsequent exploration of Mars. These systems will require high-temperature materials to meet the operating conditions with appropriate reliability and safety built into these systems through the selection and testing of appropriate materials. The application of materials for nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP) systems and the feasibility issues identified for their use will be discussed. Some mechanical property measurements have been obtained, and compatibility tests were conducted to help identify feasibility issues. 3 refs., 1 fig., 4 tabs.
Date: January 1, 1991
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Examination of the first irradiated LOFT fuel module

Description: The first Loss-of-Fluid Test (LOFT) center fuel module was nondestructively examined in order to assess any changes after power range testing and three large-break loss-of-coolant experiments (LOCEs). The examination consisted of evaluation of LOCE measurement data; measurement of withdrawal forces during removal of the module from the reactor; poolside examination of the exposed fuel module surfaces, using an underwater periscope, 35-mm camera, and closed circuit television; and poolside measurements of the rod-to-rod spacing, using a Sulo probe. The performance of the equipment is assessed from the results of the examination. Color standards are required for underwater color photography, and fuel rod deflection must be considered in evaluting rod-to-rod spaces.
Date: January 1, 1981
Creator: Cook, J.A. & Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Advanced far infrared detector and double donor studies in Ge

Description: This has application to astronomy and astrophysics. Selenium in Ge has been studied with a doping technique which limits complex formation. Only one ionization level has been found to correspond to selenium, which presumably occupies a substitutional site. This level is extremely unstable and its concentration decreases after annealing at 400C. Future work is planned to anneal the fast neutron damage before much selenium has formed in the {sup 74/76}Ge samples. It is expected that the observed selenium level can be better characterized and the missing selenium level is more likely to be discovered if other defects are removed before {sup 77}Se formation.
Date: December 1, 1994
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Advanced far infrared blocked impurity band detectors based on germanium liquid phase epitaxy

Description: This research has shown that epilayers with residual impurity concentrations of 5 x 10{sup 13} cm{sup {minus}3} can be grown by producing the purest Pb available in the world. These epilayers have extremely low minority acceptor concentrations, which is ideal for fabrication of IR absorbing layers. The Pb LPE growth of Ge also has the advantageous property of gettering Cu from the epilayer and the substrate. Epilayers have been grown with intentional Sb doping for IR absorption on lightly doped substrates. This research has proven that properly working Ge BIB detectors can be fabricated from the liquid phase as long as pure enough solvents are available. The detectors have responded at proper wavelengths when reversed biased even though the response did not quite reach minimum wavenumbers. Optimization of the Sb doping concentration should further decrease the photoionization energy of these detectors. Ge BIB detectors have been fabricated that respond to 60 cm{sup {minus}1} with low responsivity. Through reduction of the minority residual impurities, detector performance has reached responsivities of 1 A/W. These detectors have exhibited quantum efficiency and NEP values that rival conventional photoconductors and are expected to provide a much more sensitive tool for new scientific discoveries in a number of fields, including solid state studies, astronomy, and cosmology.
Date: May 1, 1998
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Weapons-grade plutonium dispositioning. Volume 4. Plutonium dispositioning in light water reactors

Description: This study is in response to a request by the Reactor Panel Subcommittee of the National Academy of Sciences (NAS) Committee on International Security and Arms Control (CISAC) to evaluate the feasibility of using plutonium fuels (without uranium) for disposal in existing conventional or advanced light water reactor (LWR) designs and in low temperature/pressure LWR designs that might be developed for plutonium disposal. Three plutonium-based fuel forms (oxides, aluminum metallics, and carbides) are evaluated for neutronic performance, fabrication technology, and material and compatibility issues. For the carbides, only the fabrication technologies are addressed. Viable plutonium oxide fuels for conventional or advanced LWRs include plutonium-zirconium-calcium oxide (PuO{sub 2}-ZrO{sub 2}-CaO) with the addition of thorium oxide (ThO{sub 2}) or a burnable poison such as erbium oxide (Er{sub 2}O{sub 3}) or europium oxide (Eu{sub 2}O{sub 3}) to achieve acceptable neutronic performance. Thorium will breed fissile uranium that may be unacceptable from a proliferation standpoint. Fabrication of uranium and mixed uranium-plutonium oxide fuels is well established; however, fabrication of plutonium-based oxide fuels will require further development. Viable aluminum-plutonium metallic fuels for a low temperature/pressure LWR include plutonium aluminide in an aluminum matrix (PuAl{sub 4}-Al) with the addition of a burnable poison such as erbium (Er) or europium (Eu). Fabrication of low-enriched plutonium in aluminum-plutonium metallic fuel rods was initially established 30 years ago and will require development to recapture and adapt the technology to meet current environmental and safety regulations. Fabrication of high-enriched uranium plate fuel by the picture-frame process is a well established process, but the use of plutonium would require the process to be upgraded in the United States to conform with current regulations and minimize the waste streams.
Date: June 1, 1993
Creator: Sterbentz, J. W.; Olsen, C. S. & Sinha, U. P.
Partner: UNT Libraries Government Documents Department